Incendiary composition consisting of titanium, aluminum-magnesium alloy, and inorganic oxidizer salt



3,396,060 INCENDIARY COMPOSITION CONSISTING F TITANIUM, ALUMINUM MAGNESIUM AL- LOY, AND INORGANIC OXIDIZER SALT Marshall Piccone, Denver, Colo., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Army No Drawing. Filed Nov. 2, 1960, Ser. No. 66,892 3 Claims. (Cl. 149-42) This invention relates to a long burning composition for incendiary purposes and has for an object to provide such a composition which is lighter in weight, safer for a given particle size, yet capable of burning almost as long as does zirconium in the same particle sizes.

A chief advantage of this invention is the provision of an incendiary material and projectile which is lighter in weight and much needed from a logistical standpoint where a small saving in weight becomes important when considered from the standpoint of hundreds and thousands of rounds to be shipped and carried to a theater of operations.

There has been no knownrule whereby the burning rate of a particular size of particle or granule of lightweight metal can be predicted. Although it is known that burning rate is affected by surface area, size of particle, type of surface, and porosity, nevertheless it cannot be foretold, for example, what will be the effect of enlarging the particle size some number of times for a general globular shape. It is known that a small particle size in a number of metals enables them to be burned while in a much larger particle size they seem non-combustible. The boundary line between these two states is not definite because a difiicult consumable size of metal may nevertheless be ignited even though with greater difficulty and at a higher temperature. This precise nature of the difliculty and corresponding ignition temperature is not known. This is why this problem is not simply one of increasing the size of particle to obtain longer burning light metal.

Titanium in fine common sizes has been suggested as a possible primer fuel when rapid burning is not objectionable for projectiles. Larger sizes in the sieve series of titanium have not been available commercially until after this invention.

According to this invention it has been discovered that when titanium was granulated into a 20 to 60 mesh in the United States Standard Sieve Series it was difiicult to ignite, yet when eventually ignited it burned for a satisfactorily long time and became suitable for use in incendiary projectiles against aircraft. A suitable ignition material for titanium was found to be equal quantities by weight of a powdered inorganic oxidizing salt such as potassium perchlorate or barium nitrate or ammonium nitrate in their usual powdered form mixed with 50/50 alloy of aluminum and magnesium in the usual powdered form in which it has been used previously in incendiary States Patent 0 3,396,060 Patented Aug. 6, 1968 ice projectiles. The new result has been a long burst duration with lighter weight than has heretofore been obtained without titanium. As little as 5% titanium by weight added to the previously standardized incendiary composition for aircraft projectiles of 47 /2 oxidizing agent and 47 /2 of a 50/50 aluminum and magnesium gave a duration of burning almost equal to that of heavier incendiary projectiles. Increased amounts of titanium in that larger particle size gave increased burst duration for the incendiaries up to about 75% of titanium with 12 /2% by weight of the powdered 50/50 alloy of aluminum and magnesium and 12 /2 by weight of powdered potassium perchlorate. Using particle sizes of titanium smaller than mesh effected an objectionable shorter duration of burning. Using particle sizes of titanium larger than 20 mesh rendered ignition more difficult and created a tendency for the titanium to segregate or separate from the mixture. About 50% of titanium by weight was perhaps the best amount with 25% by weight of the aluminummagnesium alloy mentioned and 25% by weight of one of the oxidizing materials named. The material containing 50% by weight of titanium gave a burst duration of about 225 milliseconds as compared with a maximum burst duration of about 300 milliseconds for the 20 to 60 mesh particle size of zirconium material, although a long burst duration for lighter weight material has been long sought after. The by weight of titanium gave a burst duration of better than 275 milliseconds. Beyond about 75 of titanium indicated reliability of ignition has not been obtainable.

The equivalent oxidizing materials named are not the only equivalents of the potassium perchlorate.

I claim:

1. An incendiary composition for projectiles consisting of between about 5% to 75% by weight of titanium of a size about 20 to 60 mesh, between about 47 /2% and 12 /2 by weight of a powdered 50/50 alloy of aluminum and magnesium, and between about 47 /2% and 12 /2% by weight of a powdered inorganic oxidizing salt.

2. A composition according to claim 1 in which said oxidizing salt is from the class consisting of potassium perchlorate, barium nitrate, and ammonium nitrate.

3. A composition according to claim 2 in which said titanium is about 50% by weight of the composition, the balance being about 25 by weight of oxidizing salt and about 25 by weight of said 50/50 aluminum-magnesium.

References Cited UNITED STATES PATENTS 2,775,514 12/1956 Wainer 52-2 2,951,752 9/1960 Stevenson 5224 2,992,086 7/1961 Porter l4942 3,028,808 4/1962 Porter et al l4942 CARL D. QUARFORTH, Primary Examiner. S. J. LECHERT, JR., Assistant Examiner. 

1. AN INCENDIARY COMPOSITION FOR PROJECTILES CONSISTING OF BETWEEN ABOUT 5% TO 75% BY WEIGHT OF TITANIUM OF A SIZE ABOUT 20 TO 60 MESH, BETWEEN ABOUT 47 1/2% AND 12 1/2 % BY WEIGHT OF A POWDERED 50/50 ALLOY OF ALUMINUM AND MAGNESIUM, AND BETWEEN ABOUT 47 1/2 % AND 12 1/2 % BY WEIGHT OF A POWDERED INORGANIC OXIDIZING SALT. 